McDonagh, Elaine L. and King, Brian A. and Bryden, Harry B. and Courtois, Peggy and Szuts, Zoltan and Baringer, Molly and Cunningham, Stuart A. and Atkinson, Chris and McCarthy, Gerard (2015) Continuous Estimate of Atlantic Oceanic Freshwater Flux at 26.5°N. Journal of Climate, 28. pp. 8888-8906. ISSN 0894-8755

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Abstract

The first continuous estimates of freshwater flux across 26.5°N are calculated using observations from the RAPID–MOCHA–Western Boundary Time Series (WBTS) and Argo floats every 10 days between April 2004 and October 2012. The mean plus or minus the standard deviation of the freshwater flux (FW) is −1.17 ± 0.20 Sv (1 Sv ≡ 106 m3 s−1; negative flux is southward), implying a freshwater divergence of −0.37 ± 0.20 Sv between the Bering Strait and 26.5°N. This is in the sense of an input of 0.37 Sv of freshwater into the ocean, consistent with a region where precipitation dominates over evaporation. The sign and the variability of the freshwater divergence are dominated by the overturning component (−0.78 ± 0.21 Sv). The horizontal component of the freshwater divergence is smaller, associated with little variability and positive (0.35 ± 0.04 Sv). A linear relationship, describing 91% of the variance, exists between the strength of the meridional overturning circulation (MOC) and the freshwater flux (−0.37 − 0.047 Sv of FW per Sverdrups of MOC). The time series of the residual to this relationship shows a small (0.02 Sv in 8.5 yr) but detectable decrease in the freshwater flux (i.e., an increase in the southward freshwater flux) for a given MOC strength. Historical analyses of observations at 24.5°N are consistent with a more negative freshwater divergence from −0.03 to −0.37 Sv since 1974. This change is associated with an increased southward freshwater flux at this latitude due to an increase in the Florida Straits salinity (and therefore the northward salinity flux).

Item Type:	Article
Keywords:	Circulation/ Dynamics; Meridional overturning circulation; Atm/Ocean Structure/ Phenomena; Freshwater; Physical Meteorology and Climatology; Salinity;
Academic Unit:	Faculty of Social Sciences > Geography Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
Item ID:	12190
Identification Number:	https://doi.org/10.1175/JCLI-D-14-00519.1
Depositing User:	Gerard McCarthy
Date Deposited:	22 Jan 2020 15:36
Journal or Publication Title:	Journal of Climate
Publisher:	American Meteorological Society
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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